1. Field of the Invention
The present invention relates to an apparatus with a detector for detecting an object to be detected such as a recording medium and, more particularly, to an image recording apparatus provided with a paper presence/absence detecting sensor for monitoring a conveying condition of paper on a paper conveying path.
2. Related Background Art
A signal output from a paper presence/absence detecting sensor provided to a paper conveying path in an image recording apparatus is not received for a predetermined debouncing time to prevent chattering due to noise upon operation of the sensor, and when a signal from the sensor continues beyond the debouncing time, paper presence/absence information is determined.
In such an image recording apparatus, a paper size is detected by a sensor provided to, e.g., a feed paper cassette, and registration rollers are driven for a time corresponding to the detected paper size.
However, in the above-mentioned apparatus, the predetermined debouncing time is always set to detect the presence/absence of paper. On the other hand, a common sensor is often used for both jam detection and paper size detection. When the debouncing time is shortened, chattering cannot be prevented, and the sensor may make erroneous detection, thus causing troubles such as erroneous operations. Conversely, when the debouncing time is prolonged, jam detection cannot be performed.
Since the registration rollers are driven by a length obtained by the paper size detection, if selected paper is shorter than the paper size obtained by the paper size detection or paper is fed from, e.g., a universal cassette, the registration rollers are driven for a time longer than the actual paper size, thus causing anomalous temperature rise, deterioration of the registration rollers, a decrease in service life of a registration clutch, and the like.